Digital interface modules (DIMs) for flexibly distributing digital and/or analog communications signals in wide-area analog distributed antenna systems (DASs)

ABSTRACT

Embodiments of the disclosure relate to digital interface modules (DIMs) for flexibly distributing digital and/or analog communications signals in wide-area analog distributed antenna systems (DASs). In this regard, in one aspect, a DIM is a multi-functional device capable of distributing the digital and/or analog communications signals to a local-area DASs in the wide-area DAS. The DIM comprises a digital communications interface for coupling with a digital signal source, an analog local distribution interface for coupling with an analog signal source, and at least one digital remote distribution interface for coupling with a head-end unit (HEU) of the local-area DAS. By employing the DIM in the wide-area DAS, it is possible to flexibly reconfigure the wide-area DAS for distributing digital and/or analog communications signals over the digital communications mediums.

PRIORITY APPLICATION

This application is a continuation of U.S. application Ser. No.15/475,589, filed Mar. 31, 2017, which is a continuation ofInternational Application No. PCT/IL15/051217, filed on Dec. 15, 2015,which claims the benefit of priority under 35 U.S.C. § 119 of U.S.Provisional Application No. 62/093,649, filed on Dec. 18, 2014, thecontents of which are relied upon and incorporated herein by referencein their entireties.

BACKGROUND

The disclosure relates generally to distribution of communicationssignals in a distributed antenna system (DAS), and more particularly toflexibly distributing digital and/or analog communications signalsbetween analog DASs over digital communications mediums.

Wireless customers are increasingly demanding digital data services,such as streaming video signals. Concurrently, some wireless customersuse their wireless devices in areas that are poorly served byconventional cellular networks, such as inside certain buildings orareas where there is little cellular coverage. One response to theintersection of these two concerns has been the use of DASs. DASs can beparticularly useful when deployed inside buildings or other indoorenvironments where client devices may not otherwise be able toeffectively receive radio frequency (RF) signals from a source. DASsinclude remote antenna units (RAUs) configured to receive and transmitcommunications signals to client devices within the antenna range of theRAUs.

A typical DAS comprises a head-end unit communicatively coupled to oneor more remote unit groups, each comprising at least one remote unit.The remote unit may be an RAU that is configured to wirelesslydistribute communications signals to and from the head-end unit. Thehead-end unit is configured to receive and distribute the communicationssignals to a variety of wireless services, such as wideband codedivision multiple access (WCDMA), long-term evolution (LTE), andwireless local area network (WLAN) communications services. Todistribute such wireless communications services in a DAS, the wirelesscommunications services can be provided in the form of digitalcommunications signals and/or analog communications signals to thehead-end unit of the DAS. Thus, the DAS may be configured to receive anddistribute the digital communications signals and/or analogcommunications signals in either analog or digital form. Analogcommunications signals may be directly modulated onto a carrier signalfor transmission over an analog communications medium. Digitalcommunications signals, in contrast, are signals generated by samplingand digitizing an analog communications signal before modulating ontothe carrier signal. DASs configured to directly distribute analogcommunications signals may be referred to as analog DASs. DASsconfigured to directly distribute digital communications signals may bereferred to as digital DASs.

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinency of any cited documents.

SUMMARY

Embodiments of the disclosure relate to digital-analog interface modules(DAIMs) and digital interface modules (DIMs) for flexibly distributingdigital and/or analog communications signals in wide-area analogdistributed antenna systems (DASs). A wide-area DAS typically comprisesa plurality of local-area DASs interconnected via digital communicationsmediums. Any of the plurality of local-area DASs may be configured as amain DAS to efficiently receive and redistribute digital and/or analogcommunications signals to rest of the local-area DASs in the wide-areaDAS. In a non-limiting example, the main DAS in the wide-area DAS may becollocated with installed telecommunications equipment (e.g., basetransceiver stations and digital baseband units) to avoid additionalinstallation costs, reduce power consumption, and improve operationefficiency.

In this regard, in one embodiment, a DAIM is provided asmulti-functional equipment in the main DAS for receiving andredistributing digital and/or analog communications signals to rest ofthe local-area DASs in the wide-area DAS. The DAIM comprises an analogradio frequency (RF) communications signal interface for coupling withan analog signal source, a digital communications interface for couplingwith a digital signal source, an analog local distribution interface forcoupling with a remote antenna unit (RAU), and at least one digitalremote distribution interface for coupling with a head-end unit (HEU) ofa local-area DAS. Furthermore, a plurality of DAIMs may beinterconnected via respective digital bus interfaces to concurrentlysupport the plurality of local-area DASs in the wide-area DAS. Inanother embodiment, a DIM is provided in the main DAS as an alternativeto the DAIM. The DIM is a modified DAIM and comprises a digitalcommunications interface for coupling with a digital signal source, ananalog local distribution interface for coupling with an analog signalsource, and at least one digital remote distribution interface forcoupling with the HEU of the remote local-area DAS. Furthermore, aplurality of DIMs may be interconnected via the respective digital businterfaces to concurrently support the plurality of local-area DASs inthe wide-area DAS. By employing the DAIM or the DIM in the wide-areaDAS, it is possible to flexibly reconfigure the wide-area DAS fordistributing digital and/or analog communications signals over thedigital communications mediums.

An additional embodiment of the disclosure relates to a DIM in a mainDAS to support a wide-area DAS. The DIM comprises at least one digitalremote distribution interface to be coupled with a remote DAS componentin a remote DAS in the wide-area DAS. The DIM also comprises an analoglocal distribution interface configured to receive a downlink analogradio frequency (RF) signal from a radio interface module (RIM) in themain DAS. The DIM also comprises an analog-to-digital (A/D) convertercoupled to the analog local distribution interface. The A/D converter isconfigured to receive the downlink analog RF signal from the analoglocal distribution interface. The A/D converter is also configured toconvert the downlink analog RF signal to generate a downlink digital RFsignal.

The DIM also comprises a digital signal processing circuit coupled tothe A/D converter and the at least one digital remote distributioninterface. The digital signal processing circuit is configured toreceive the downlink digital RF signal from the A/D converter. Thedigital signal processing circuit is also configured to convert thedownlink digital RF signal to generate one or more first downlinkdigital RF signals. The digital signal processing circuit is alsoconfigured to combine one or more respective first downlink digital RFsignals to generate a combined downlink digital RF signal. The digitalsignal processing circuit is also configured to provide the combineddownlink digital RF signal to the at least one digital remotedistribution interface to be distributed to the remote DAS component.

An additional embodiment of the disclosure relates to an opticalfiber-based wide-area DAS. The optical fiber-based wide-area DAScomprises a main DAS comprising a main HEU. The main HEU comprises oneor more RIMs communicatively coupled to one or more base transceiverstations (BTSs). The main HEU also comprises an RF combiner/splittercoupled to the one or more RIMs. The main HEU also comprises an opticalsplitter/combiner coupled to the RF combiner/splitter. The main HEU alsocomprises one or more main-HEU DIMs coupled to the opticalsplitter/combiner, wherein each of the one or more main-HEU DIMs iscoupled to a respective optical fiber-based downlink digitalcommunications medium via a respective electrical-to-optical (E/O)converter and a respective optical fiber-based uplink digitalcommunications medium via a respective optical-to-electrical (O/E)converter. The optical fiber-based wide-area DAS also comprises one ormore remote DASs comprising one or more remote HEUs, respectively. Aremote HEU among the one or more remote HEUs comprises one or moreremote-HEU DIMs corresponding to one or more RF bands, respectively,wherein at least one remote-HEU DIM among the one or more remote-HEUDIMs comprised in the remote HEU is configured to interface with arespective main-HEU DIM in the main HEU. The at least one remote-HEU DIMconfigured to interface with the respective main-HEU DIM in the main HEUis coupled to the respective optical fiber-based downlink digitalcommunications medium via a respective remote-HEU O/E converter and iscoupled to the respective optical fiber-based uplink digitalcommunications medium via a respective remote-HEU E/O converter. Theremote HEU among the one or more remote HEUs also comprises a remote-HEURF combiner/splitter coupled to the one or more remote-HEU DIMs. Theremote HEU among the one or more remote HEUs also comprises a remote-HEUoptical splitter/combiner coupled to the remote-HEU RFcombiner/splitter. The remote HEU among the one or more remote HEUs alsocomprises one or more remote-HEU optical interface modules (OIMs)coupled to the remote-HEU optical splitter/combiner, wherein the one ormore OIMs are coupled with one or more remote-DAS RAUs.

An additional embodiment of the disclosure relates to a method forreconfiguring an existing HEU in a DAS with DIMs. The method comprisesreplacing one or more OIMs in the existing HEU with one or more DIMs.For each of the one or more DIMs, the method also comprises coupling adigital communications interface comprised in the DIM to a respectivedigital signal source. For each of the one or more DIMs, the method alsocomprises coupling at least one digital remote distribution interfacecomprised in the DIM to a respective downlink digital communicationsmedium and a respective uplink digital communications medium. For eachof the one or more DIMs, the method also comprises coupling an analoglocal distribution interface comprised in the DIM to a respective RIM.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from the description or recognized by practicing theembodiments as described in the written description and claims hereof,as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understand the natureand character of the claims. The accompanying drawings are included toprovide a further understanding, and are incorporated in and constitutea part of this specification. The drawings illustrate one or moreembodiment(s), and together with the description serve to explainprinciples and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary analog distributed antennasystem (DAS);

FIG. 2 is a schematic diagram of an exemplary wide-area analog DASconsisting of a plurality of local-area analog DASs wherein a local-areaanalog DAS among the plurality of local-area analog DASs is configuredas a main analog DAS of the wide-area analog DAS;

FIG. 3 is a schematic diagram of an exemplary digital-analog interfacemodule (DAIM) configured to be retrofitted into the chassis of a mainhead-end unit (HEU) in the wide-area analog DAS of FIG. 2 fordistributing digital and/or analog communications signals in thewide-area analog DAS over digital communications mediums;

FIG. 4 is a schematic diagram of an exemplary digital interface module(DIM) that configured to be retrofitted into the chassis of a pluralityof remote HEUs as well as a main HEU in the wide-area analog DAS of FIG.2 for distributing digital and/or analog communications signals in thewide-area analog DAS over digital communications mediums;

FIG. 5A is a schematic diagram of an exemplary main HEU comprising aplurality of DAIMs that are interconnected to an interconnection digitalbus via a plurality of digital bus interfaces and configured to share aplurality of downlink communications signals;

FIG. 5B is a schematic diagram of an exemplary main HEU comprising theplurality of DAIMs in FIG. 5A that are interconnected to theinterconnection digital bus in FIG. 5A via the plurality of digital businterfaces in FIG. 5A and configured to share a plurality of uplinkcommunications signals;

FIG. 6 is a schematic diagram of an exemplary optical fiber-basedwide-area DAS configured to distribute digital and analog communicationssignals from a main HEU to one or more remote HEUs over opticalfiber-based digital communications mediums, wherein the main HEU isreconfigured by retrofitting one or more of the DAIMs illustrated inFIG. 3 into the existing chassis of a main HEU in FIG. 2;

FIG. 7 is a flowchart of an exemplary HEU configuration processreconfiguring the main HEU in FIG. 2 with one or more of the DAIMs inFIG. 6;

FIG. 8 is a schematic diagram of an exemplary optical fiber-basedwide-area DAS configured to distribute digital and analog communicationssignals from a main HEU to the one or more remote HEUs in FIG. 6 overthe optical fiber-based digital communications mediums in FIG. 6,wherein the main HEU is reconfigured by retrofitting one or more of theDIMs illustrated in FIG. 4 into the existing chassis of a main HEU inFIG. 2;

FIG. 9 is a flowchart of an exemplary HEU configuration processreconfiguring the main HEU in FIG. 2 with one or more main-HEU DIMs inFIG. 8;

FIG. 10 is a schematic diagram of an exemplary DAS comprising a main HEUcoupled to a remote HEU over a plurality of optical fiber-basedcommunications mediums;

FIG. 11 is a schematic diagram of an exemplary DAS comprising a main HEUcoupled to a remote HEU using wavelength-division multiplexing (WDM);

FIG. 12 is a schematic diagram of an exemplary DAS wherein a main HEUand a remote HEU are configured to concurrently distribute digitaland/or analog communications signals using a plurality of DAIMs and aplurality of DIMs;

FIG. 13 is a schematic diagram of an exemplary DAS wherein a main HEUand a remote HEU are configured to concurrently distribute digitaland/or analog communications signals using WDM; and

FIG. 14 is a partially schematic cut-away diagram of an exemplarybuilding infrastructure in which an analog DAS, which can include theDAIM in FIG. 3 or the DIM in FIG. 4 to support the distribution ofdigital and/or communications signals, can be employed.

DETAILED DESCRIPTION

Various embodiments will be further clarified by the following examples.

Embodiments of the disclosure relate to digital-analog interface modules(DAIMs) and digital interface modules (DIMs) for flexibly distributingdigital and/or analog communications signals in wide-area analogdistributed antenna systems (DASs). A wide-area DAS typically comprisesa plurality of local-area DASs interconnected via digital communicationsmediums. Any of the plurality of local-area DASs may be configured as amain DAS to efficiently receive and redistribute digital and/or analogcommunications signals to rest of the local-area DASs in the wide-areaDAS. In a non-limiting example, the main DAS in the wide-area DAS may becollocated with installed telecommunications equipment (e.g., basetransceiver stations and digital baseband units) to avoid additionalinstallation costs, reduce power consumption, and improve operationefficiency.

In this regard, in one aspect, a DAIM is provided as multi-functionalequipment in the main DAS for receiving and redistributing digitaland/or analog communications signals to rest of the local-area DASs inthe wide-area DAS. The DAIM comprises an analog radio frequency (RF)communications signal interface for coupling with an analog signalsource, a digital communications interface for coupling with a digitalsignal source, an analog local distribution interface for coupling witha remote antenna unit (RAU), and at least one digital remotedistribution interface for coupling with a head-end unit (HEU) of alocal-area DAS. Furthermore, a plurality of DAIMs may be interconnectedvia respective digital bus interfaces to concurrently support theplurality of local-area DASs in the wide-area DAS.

In another aspect, a DIM is provided in the main DAS as an alternativeto the DAIM. The DIM is a modified DAIM and comprises a digitalcommunications interface for coupling with a digital signal source, ananalog local distribution interface for coupling with an analog signalsource, and at least one digital remote distribution interface forcoupling with the HEU of the remote local-area DAS. Furthermore, aplurality of DIMs may be interconnected via the respective digital businterfaces to concurrently support the plurality of local-area DASs inthe wide-area DAS.

By employing the DAIM or the DIM in the wide-area DAS, it is possible toflexibly reconfigure the wide-area DAS for distributing digital and/oranalog communications signals over the digital communications mediums.

Before discussing examples of a DAIM supporting flexible distribution ofdigital and/or analog communications signals between analog DASsstarting at FIG. 3, discussions of an exemplary local-area analog DASand an exemplary wide-area analog DAS that support only analog wirelesscommunications services are first provided with references to FIGS. 1and 2. The discussion of specific exemplary aspects of flexiblydistributing digital and/or analog communications signals between analogDASs using the DAIM is provided starting at FIG. 3.

In this regard, FIG. 1 illustrates distribution of wirelesscommunications services to coverage areas 10(1)-10(N) of an analog DAS12, wherein ‘N’ is the number of coverage areas. These wirelesscommunications services can include cellular services, wireless servicessuch as radio frequency (RF) identification (RFID) tracking, WirelessFidelity (Wi-Fi), local area network (LAN), and combinations thereof, asexamples. The coverage areas 10(1)-10(N) may be remotely located. Inthis regard, the remote coverage areas 10(1)-10(N) are created by andcentered on remote antenna units (RAUs) 14(1)-14(N) connected to ahead-end unit (HEU) 16 (e.g., a head-end controller or head-endequipment or central unit). The HEU 16 may be communicatively coupled toa base transceiver station (BTS) 18. In this regard, the HEU 16 receivesdownlink analog RF communications signals 20D from the BTS 18 to bedistributed to the remote antenna units 14(1)-14(N). The remote antennaunits 14(1)-14(N) are configured to receive the downlink analog RFcommunications signals 20D from the HEU 16 over an analog communicationsmedium 22 to be distributed to the respective remote coverage areas10(1)-10(N) of the remote antenna units 14(1)-14(N). In a non-limitingexample, the analog communications medium 22 may be a wiredcommunications medium, a wireless communications medium, or an opticalfiber-based communications medium. Each remote antenna unit 14(1)-14(N)may include an RF transmitter/receiver (not shown) and a respectiveantenna 24(1)-24(N) operably connected to the RF transmitter/receiver towirelessly distribute the wireless communications services to clientdevices 26 within their respective remote coverage areas 10(1)-10(N).The remote antenna units 14(1)-14(N) are also configured to receiveanalog uplink RF communications signals 20U from the client devices 26in their respective remote coverage areas 10(1)-10(N) to be distributedto the BTS 18. The size of a given remote coverage area 10(1)-10(N) isdetermined by the amount of RF power transmitted by the respectiveremote antenna unit 14(1)-14(N), the receiver sensitivity, antenna gainand the RF environment, as well as by the RF transmitter/receiversensitivity of the client device 26. The client devices 26 usually havea fixed maximum RF receiver sensitivity, so that the above-mentionedproperties of the remote antenna units 14(1)-14(N) mainly determine thesize of their respective remote coverage areas 10(1)-10(N).

The analog DAS 12 is typically deployed to extend indoor coverage of thewireless communications services inside a building. In this regard, theanalog DAS 12 may be considered as a local-area DAS for the building. Insome cases, a wide-area analog DAS is deployed to provide the wirelesscommunications service to multiple buildings each covered by alocal-area DAS like the analog DAS 12. In this regard, FIG. 2 is aschematic diagram of an exemplary wide-area analog DAS 30 consisting ofa plurality of local-area analog DASs 32(1)-32(N) wherein a local-areaanalog DAS 32(X) (1≤X≤N) among the plurality of local-area analog DASs32(1)-32(N) is configured as a main analog DAS 34 of the wide-areaanalog DAS 30. In this regard, the wide-area analog DAS 30 is configuredaccording to a star-topology, wherein the main analog DAS 34 serves as agateway for rest of the plurality of local-area analog DASs 32(1)-32(N)in the wide-area analog DAS 30. The star-topology allows adding a newlocal-area analog DAS or removing an existing local-area analog DASwithout impacting operations of the wide-area analog DAS 30.

In this regard, with continuing reference to FIG. 2, in a non-limitingexample, the main analog DAS 34 comprised in the local-area analog DAS32(X) may be collocated with one or more BTSs 36(1)-36(M). The mainanalog DAS 34 comprises a main HEU 38, which is a main DAS component andcomprises a main-HEU DAS radio interface unit (RIU) (DAS-RIU) 40 and amain-HEU DAS optical interface unit (OIU) (DAS-OIU) 42. In anon-limiting example, the main HEU 38 may be a central unit. Themain-HEU DAS-RIU 40 comprises one or more main-HEU RIMs 44(1)-44(M)coupled to the one or more BTSs 36(1)-36(M) for communicating one ormore downlink analog RF communications signals 46(1)-46(M) and one ormore uplink analog RF communications signals 48(1)-48(M), respectively.On a downlink direction 50, the one or more main-HEU RIMs 44(1)-44(M)adapt the one or more downlink analog RF communications signals46(1)-46(M) into one or more downlink analog RF signals 52(1)-52(M) thatare suited for distribution in the wide-area analog DAS 30. The one ormore downlink analog RF signals 52(1)-52(M) are provided to an RFcombiner/splitter 54 wherein the one or more downlink analog RF signals52(1)-52(M) are combined to generate a combined downlink analog RFsignal 56. The combined downlink analog RF signal 56 is subsequentlyreceived by an optical splitter/combiner 58 in the main-HEU DAS-OIU 42,wherein the combined downlink analog RF signal 56 is first split andthen recombined to generate a plurality of second downlink analog RFsignals 60(1)-60(N). The main-HEU DAS-OIU 42 comprises a plurality ofOIMs 62(1)-62(N) that correspond to the plurality of local-area analogDASs 32(1)-32(N), respectively. Among the plurality of OIMs 62(1)-62(N),the OIM 62(X) (1≤X≤N) is configured to be coupled to an RAU 64 that isassociated with the main analog DAS 34. In this regard, the RAU 64 isalso a main DAS component. The plurality of OIMs 62(1)-62(N) receivesand converts the plurality of second downlink analog RF signals60(1)-60(N) into a plurality of combined downlink optical RF signals66(1)-66(N), respectively. Among the plurality of combined downlinkoptical RF signals 66(1)-66(N), the combined downlink optical RF signal66(X) (1≤X≤N) is provided to the RAU 64 while the rest of the pluralityof combined downlink optical RF signals 66(1)-66(N) are provided to theplurality of local-area analog DASs 32(1)-32(N), respectively.

With continuing reference to FIG. 2, in an uplink direction 68, theplurality of OIMs 62(1)-62(N) receive a plurality of combined uplinkoptical RF signals 70(1)-70(N) from the plurality of local-area analogDASs 32(1)-32(N), respectively. Among the plurality of combined uplinkoptical RF signals 70(1)-70(N), the combined uplink optical RF signal70(X) (1≤X≤N) may be received from the RAU 64. The plurality of OIMs62(1)-62(N) convert the plurality of combined uplink optical RF signals70(1)-70(N) into a plurality of second uplink analog RF signals72(1)-72(N). The plurality of second uplink analog RF signals72(1)-72(N) are received by the optical splitter/combiner 58 wherein theplurality of second uplink analog RF signals 72(1)-72(N) are split andrecombined to generate a combined uplink analog RF signal 74. Thecombined uplink analog RF signal 74 is subsequently received by the RFcombiner/splitter 54 wherein the combined uplink analog RF signal 74 issplit into one or more uplink analog RF signals 76(1)-76(M). The one ormore main-HEU RIMS 44(1)-44(M) adapt the one or more uplink analog RFsignals 76(1)-76(M) to generate the one or more uplink analog RFcommunications signals 48(1)-48(M) that are suited for distribution tothe one or more BTSs 36(1)-36(M).

With continuing reference to FIG. 2, in contrast to the local-areaanalog DAS 32(X) that is configured as the main analog DAS 34, the restof the plurality of local-area analog DASs 32(1)-32(N) may be treated asremote local-area analog DASs in the wide-area analog DAS 30. On thedownlink direction 50, each of the plurality of local-area analog DASs32(1)-32(N) receives a respective downlink optical RF signal among theplurality of combined downlink optical RF signals 66(1)-66(N) from themain analog DAS 34 and distributes to one or more respective RAUs78(1)-78(R), wherein ‘R’ may represent a different positive integernumber among the plurality of local-area analog DASs 32(1)-32(N). Inthis regard, the one or more respective RAUs 78(1)-78(R) are one or moreremote DAS components. In the uplink direction 68, each of the pluralityof local-area analog DASs 32(1)-32(N) provides a respective uplinkoptical RF signal among the plurality of combined uplink optical RFsignals 70(1)-70(N) to the main analog DAS 34. In this regard, thelocal-area analog DAS 32(1) is discussed next as a non-limiting exampleof the functional aspects involved in the plurality of local-area analogDASs 32(1)-32(N) (N≠X).

With continuing reference to FIG. 2, the local-area analog DAS 32(1)comprises an optical-to-electrical (O/E) converter 80(1) and anelectrical-to-optical (E/O) converter 82(1). The local-area analog DAS32(1) also comprises a remote HEU 84(1) that is coupled to the O/Econverter 80(1) and the E/O converter 82(1). In this regard, theplurality of local-area analog DASs 32(1)-32(N) comprises a plurality ofremote HEUs 84(1)-84(N), respectively. In a non-limiting example, theplurality of remote HEUs 84(1)-84(N) is also a plurality of remote DAScomponents. The remote HEU 84(1) further comprises a remote-HEU DAS-RIU86(1) and a remote-HEU DAS-OIU 88(1). The remote-HEU DAS-RIU 86(1)comprises one or more remote-HEU RIMs 90(1)-90(S), wherein ‘S’ mayrepresent a different positive integer number among the plurality oflocal-area analog DASs 32(1)-32(N). The O/E converter 80(1) converts thecombined downlink optical RF signal 66(1) into a remote-HEU combineddownlink analog RF signal 92(1), which is subsequently received by theone or more remote-HEU RIMs 90(1)-90(S). The one or more remote-HEU RIMs90(1)-90(S) then generates one or more remote-HEU downlink analog RFsignals 94(1)-94(S), wherein each of the one or more remote-HEU downlinkanalog RF signals 94(1)-94(S) corresponds to a respective RF band (notshown). The one or more remote-HEU downlink analog RF signals94(1)-94(S) are received by a remote-HEU RF combiner/splitter 96(1) andcombined into a second remote-HEU combined downlink analog RF signal98(1). The second remote-HEU combined downlink analog RF signal 98(1) isreceived by a remote-HEU optical splitter/combiner 100(1), whereinsecond remote-HEU combined downlink analog RF signal 98(1) is firstsplit and then recombined to generate one or more third remote-HEUcombined downlink analog RF signals 102(1)-102(R). Each of the one ormore third remote-HEU combined downlink analog RF signals 102(1)-102(R)corresponds to a RAU among the one or more RAUs 78(1)-78(R) and maycomprise one or more RF bands. The remote-HEU DAS-OIU 88(1) comprisesone or more remote-HEU OIMs 104(1)-104(R) that correspond to the one ormore respective RAUs 78(1)-78(R), respectively. The one or moreremote-HEU OIMs 104(1)-104(R) receive and convert the one or more thirdremote-HEU combined downlink analog RF signals 102(1)-102(R) into one ormore remote-HEU combined downlink optical RF signals 106(1)-106(R),respectively. The one or more remote-HEU combined downlink optical RFsignals 106(1)-106(R) are then distributed to the one or more respectiveRAUs 78(1)-78(R).

With continuing reference to FIG. 2, on the uplink direction 68, the oneor more remote-HEU OIMs 104(1)-104(R) receive one or more remote-HEUcombined uplink optical RF signals 108(1)-108(R) from the one or morerespective RAUs 78(1)-78(R), respectively. The one or more remote-HEUOIMs 104(1)-104(R) then convert the one or more remote-HEU combineduplink optical RF signals 108(1)-108(R) into one or more thirdremote-HEU combined uplink analog RF signals 110(1)-110(R). Each of theone or more third remote-HEU combined uplink analog RF signals110(1)-110(R) corresponds to one or more RF bands. The one or more thirdremote-HEU combined uplink analog RF signals 110(1)-110(R) are receivedby the remote-HEU optical splitter/combiner 100(1), wherein the one ormore third remote-HEU combined uplink analog RF signals 110(1)-110(R)are combined into a second remote-HEU combined uplink analog RF signal112(1). The second remote-HEU combined uplink analog RF signal 112(1) issubsequently received by the remote-HEU RF combiner/splitter 96(1)wherein the second remote-HEU combined uplink analog RF signal 112(1) issplit into one or more remote-HEU uplink analog RF signals114(1)-114(S). Each of the one or more remote-HEU uplink analog RFsignals 114(1)-114(S) corresponds to the respective RF band. The one ormore remote-HEU uplink analog RF signals 114(1)-114(S) are then combinedinto a remote-HEU combined uplink analog RF signal 116(1), which issubsequently converted to the combined uplink optical RF signal 70(1)and provided to the OIM 62(1) in the main analog DAS 34.

As digital communication technologies become increasingly reliable andcost-effective, the wide-area analog DAS 30 may need to be upgraded todistribute digital and/or analog communications signals between theplurality of local-area analog DASs 32(1)-32(N) over digitalcommunications mediums. As a result, the main analog DAS 34 and theplurality of local-area analog DASs 32(1)-32(N) may need to be upgradedfor distributing the digital and/or analog communications signals overthe digital communications mediums. It may be desirable to retrofit newmulti-functional equipment into the chassis of the installed equipmentto reduce upgrade costs and minimize service disruptions to thewide-area analog DAS 30. In a non-limiting example, it is desirable tobe able to retrofit the new multi-functional equipment into the chassisof the main HEU 38 and/or the plurality of remote HEUs 84(1)-84(N).

In this regard, FIG. 3 is a schematic diagram of an exemplarydigital-analog interface module (DAIM) 120 that is retrofitted into thechassis of the main HEU 38 in the wide-area analog DAS 30 of FIG. 2 fordistributing digital and/or analog communications signals in thewide-area analog DAS 30 over digital communications mediums. In essence,the DAIM 120 is multi-functional device capable of distributing digitaland/or analog communications signals to the plurality of local-areaanalog DASs 32(1)-32(N) in the wide-area analog DAS 30. Elements in FIG.2 are referenced in connection with FIG. 3 and will not be re-describedherein.

With reference to FIG. 3, the DAIM 120 comprises an analogcommunications interface (P1) 122 configured to be coupled with ananalog signal source 124 for distributing analog communications signals.In a non-limiting example, the analog signal source 124 may be a BTS.The DAIM 120 also comprises a digital bus interface (P2) 126, whichfurther comprises an upstream digital bus interface (P2U) 128 and adownstream digital bus interface (P2D) 130. As will be further discussedin detail below in FIGS. 5A and 5B, the upstream digital bus interface128 and the downstream digital bus interface 130 enables the DAIM 120 tobe interconnected with other DAIMs to enable flexible digital signalsharing with the other DAIMs. The DAIM 120 also comprises at least onedigital remote distribution interface (P3) 132 configured to be coupledwith any remote HEU among the plurality of remote HEUs 84(1)-84(N) (notshown). The DAIM 120 also comprises an analog local distributioninterface (P4) 134 for distributing analog RF signals to the RAU 64 (notshown). The DAIM 120 also comprises a digital communications interface(P5) 136 to be coupled to a digital signal source 138 for distributingdigital communications signals. In a non-limiting example, the digitalsignal source 138 may be a digital baseband unit (BBU).

With continuing reference to FIG. 3, the DAIM 120 further comprises anRF conditioning circuit 140 that is coupled to the analog communicationsinterface 122 and the analog local distribution interface 134. In adownlink direction 142, the RF conditioning circuit 140 receives adownlink analog communications signal 144 from the analog signal source124 via the analog communications interface 122. The RF conditioningcircuit 140 converts the downlink analog communications signal 144 intoa downlink analog RF signal 146, which is adapted for redistribution inthe wide-area analog DAS 30. The RF conditioning circuit 140 thenprovides the downlink analog RF signal 146 to the analog localdistribution interface 134 for distribution to the RAU 64. In addition,to provide a digitized version of the downlink analog RF signal 146 tobe available for distribution, an analog-to-digital (A/D) converter 148is provided. The A/D converter 148 converts the downlink analog RFsignal 146 to generate a downlink digital RF signal 150 and provides thedownlink digital RF signal 150 to a digital signal processing circuit152. Upon receiving the downlink digital RF signal 150, the digitalsignal processing circuit 152 converts the downlink digital RF signal150 into one or more first downlink digital RF signals 154 and providesthe one or more first downlink digital RF signals 154 to the upstreamdigital bus interface 128 and the downstream digital bus interface 130.

As will be further discussed in FIGS. 5A and 5B, providing the one ormore first downlink digital RF signals 154 to the upstream digital businterface 128 and the downstream digital bus interface 130 allowsinterconnected DAIMs to receive indirectly the one or more firstdownlink digital RF signals 154. Since not all of the one or more firstdownlink digital RF signals 154 are related to the DAIM 120, a digitalsignal processing controller 156 is configured to determine one or morerespective first downlink digital RF signals (not shown), among the oneor more first downlink digital RF signals 154, that are related to theDAIM 120. In a non-limiting example, the digital signal processingcontroller 156 may be provided inside or outside the DAIM 120. In anon-limiting example, the digital signal processing controller 156 ispreconfigured to detect the one or more respective first downlinkdigital RF signals based on frequency-related information, such aschannel number in a frequency-division duplex (FDD) signal or time slotnumber in a time-division duplex (TDD) signal, carried in the one ormore first downlink digital RF signals 154. The digital signalprocessing controller 156 is communicatively coupled to the digitalsignal processing circuit 152 or embedded in the digital signalprocessing circuit 152. In this regard, the digital signal processingcircuit 152 can combine the one or more respective first downlinkdigital RF signals to generate a combined downlink digital RF signal158. Subsequently, the digital signal processing circuit 152 providesthe combined downlink digital RF signal 158 to the digital remotedistribution interface 132 for distribution to any remote HEU among theplurality of remote HEUs 84(1)-84(N).

With continuing reference to FIG. 3, the digital signal processingcircuit 152 may receive one or more second downlink digital RF signals160 from the upstream digital bus interface 128 and one or more thirddownlink digital RF signals 162 from the downstream digital businterface 130. As will be further illustrated in FIGS. 5A and 5B, theone or more second downlink digital RF signals 160 and the one or morethird downlink digital RF signals 162 are provided to the digital signalprocessing circuit 152 by other interconnected DAIMs. The digital signalprocessing circuit 152 in turn forwards the one or more second downlinkdigital RF signals 160 to the downstream digital bus interface 130 andforward the one or more third downlink digital RF signals 162 to theupstream digital bus interface 128. As previously discussed with regardto the one or more first downlink digital RF signals 154, the one ormore second downlink digital RF signals 160 and the one or more thirddownlink digital RF signals 162 received from the digital bus interface126 may not be related to the DAIM 120 as well. As such, the digitalsignal processing controller 156 is also configured to determine one ormore respective second downlink digital RF signals (not shown) among theone or more second downlink digital RF signals 160 and one or morerespective third downlink digital RF signals (not shown) among the oneor more third downlink digital RF signals 162. In this regard, thedigital signal processing circuit 152 can combine the one or morerespective second downlink digital RF signals and the one or morerespective third downlink digital RF signals into the combined downlinkdigital RF signal 158.

With continuing reference to FIG. 3, the digital signal processingcircuit 152 may also receive a downlink digital baseband signal 164 fromthe digital signal source 138 that is coupled to the digitalcommunications interface 136. In a non-limiting example, the downlinkdigital baseband signal 164 may be received from a BBU and is incompliance with a common public radio interface (CPRI) format. Thedigital signal processing circuit 152 is configured to convert thedownlink digital baseband signal 164 to generate one or more fourthdownlink digital RF signals 166. Accordingly, the digital signalprocessing circuit 152 provides the one or more fourth downlink digitalRF signals 166 to the upstream digital bus interface 128 and thedownstream digital bus interface 130. The digital signal processingcontroller 156, in turn, determines one or more respective fourthdownlink digital RF signals (not shown) among the one or more fourthdownlink digital RF signals 166 for combining with the combined downlinkdigital RF signal 158 by the digital signal processing circuit 152.

With continuing reference to FIG. 3, in an uplink direction 168, thedigital signal processing circuit 152 receives a combined uplink digitalRF signal 170 from any remote HEU among the plurality of remote HEUs84(1)-84(N) (not shown) via the digital remote distribution interface132. The digital signal processing circuit 152 splits the combineduplink digital RF signal 170 to generate one or more first uplinkdigital RF signals 172. The digital signal processing circuit 152 inturn provides the one or more first uplink digital RF signals 172 to theupstream digital bus interface 128 and the downstream digital businterface 130. As previously discussed, the one or more first uplinkdigital RF signals 170 may or may not be related to the DAIM 120. Assuch, the digital signal processing controller 156 is also configureddetermine one or more respective first uplink digital RF signals (notshown) among the one or more first uplink digital RF signals 170. As aresult, the digital signal processing circuit 152 can combine the one ormore respective first uplink digital RF signals to generate an uplinkdigital RF signal 174.

With continuing reference to FIG. 3, the digital signal processingcircuit 152 may receive one or more second uplink digital RF signals 176from the upstream digital bus 128. The digital signal processing circuit152 may also receive one or more third uplink digital RF signals 178from the downstream digital bus 130. The digital signal processingcircuit 152 in turn forwards the one or more second uplink digital RFsignals 176 to the downstream digital bus interface 130 and forwards theone or more third uplink digital RF signals 178 to the upstream digitalbus interface 128. The digital signal processing controller 156 isconfigured to determine one or more respective second uplink digital RFsignals (not shown) among the one or more second uplink digital RFsignals 176 and one or more respective third uplink digital RF signals(not shown) among the one or more third uplink digital RF signals 178.In this regard, the digital signal processing circuit 152 can combinethe one or more respective second uplink digital RF signals and the oneor more respective third uplink digital RF signals into the uplinkdigital RF signal 174.

With continuing reference to FIG. 3, the digital signal processingcircuit 152 may also receive an uplink digital baseband signal 180 fromthe digital signal source 138 that is coupled to the digitalcommunications interface 136. In a non-limiting example, the uplinkdigital baseband signal 180 may be received from a BBU and is incompliance with the CPRI format. The digital signal processing circuit152 is configured to convert the uplink digital baseband signal 180 togenerate one or more fourth uplink digital RF signals 182. Accordingly,the digital signal processing circuit 152 provides the one or morefourth uplink digital RF signals 182 to the upstream digital businterface 128 and the downstream digital bus interface 130. The digitalsignal processing controller 156, in turn, determines one or morerespective fourth downlink digital RF signals (not shown) among the oneor more fourth downlink digital RF signals 182 for combining with theuplink digital RF signal 174 by the digital signal processing circuit152.

With continuing reference to FIG. 3, the DAIM 120 further comprises adigital-to-analog (D/A) converter 184 that is coupled to the digitalsignal processing circuit 152 and the RF conditioning circuit 140. TheD/A converter 184 receives and converts the uplink digital RF signal 174to generate an uplink analog RF signal 186 and provides the uplinkanalog RF signal 186 to the RF conditioning circuit 140. Upon receivingthe uplink analog RF signal 186, the RF conditioning circuit 140provides the uplink analog RF signal 186 to the analog localdistribution interface 134 for distribution to the RAU 64 (not shown).In another aspect, the RF conditioning circuit 140 converts the uplinkanalog RF signal 186 into an uplink analog communications signal 188,which is adapted for communications to the analog signal source 124.Subsequently, the RF conditioning circuit 140 provides the uplink analogcommunications signal 188 to the analog communications interface 122 fordistribution to the analog signal source 124.

The DAIM 120 in FIG. 3 is designed and configured to be retrofitted intothe chassis of the main HEU 38 of the main analog DAS 34 in thewide-area analog DAS 30 for distributing the analog and/or digitalcommunications signals in the wide-area analog DAS 30. Although it isalso possible to retrofit the DAIM 120 into the chassis of the pluralityof remote HEUs 84(1)-84(N) for supporting the local-area analog DASs32(1)-32(N), the RF conditioning circuit 140 and the analogcommunications interface 122 in the DAIM 120 would not be utilized ifthe plurality of remote HEUs 84(1)-84(N) are not directly interactingwith the one or more BTSs 36(1)-36(M). In this regard, FIG. 4 is aschematic diagram of an exemplary digital interface module (DIM) 189that provides similar functionality to the DAIM 120 in FIG. 3. However,in the DIM 189 in FIG. 4, the analog communications interface 122 andthe RF conditioning circuit 140 of the DIM 120 are not included. As aresult, the A/D converter 148 and the D/A converter 184 of the DIM 120are directly coupled to the analog local distribution interface 134 inthe DIM 189 for receiving the downlink analog RF signal 146 andproviding the uplink analog RF signal 186, respectively. Like the DAIM120 in FIG. 3, the DIM 189 in FIG. 4 can be configured to be retrofittedinto the chassis of the plurality of remote HEUs 84(1)-84(N) as well asthe main HEU 38 in the wide-area analog DAS 30 of FIG. 2 fordistributing digital and/or analog communications signals in thewide-area analog DAS 30 over digital communications mediums. Commonelements between FIGS. 3 and 4 are shown therein with common elementnumbers, thus will not be re-described herein.

In this regard, with reference to FIG. 4, the A/D converter 148 in theDIM 189 receives the downlink analog RF signal 146 from the analog localdistribution interface 134 and converts the downlink analog RF signal146 into the downlink digital RF signal 150. The D/A converter 184converts the uplink digital RF signal 174 into the uplink analog RFsignal 186 and provides the uplink analog RF signal 186 to the analoglocal distribution interface 134. In a non-limiting example, the digitalsignal processing controller 156 may be provided inside or outside theDIM 189.

As previously discussed in reference to FIG. 3, the upstream digital businterface 128 and the downstream digital bus interface 130 enables theDAIM 120 to be interconnected with other DAIMs to support a flexibletopology of the wide-area analog DAS 30. In this regard, FIG. 5A is aschematic diagram of an exemplary main HEU 190 comprising a plurality ofDAIMs 192(1)-192(3) that are interconnected to an interconnectiondigital bus 193 via a plurality of digital bus interfaces 194(1)-194(3)and configured to share a plurality of downlink communications signals196(1)-196(3). The main HEU 190 may comprise any positive integer numberof DAIMs 192. The plurality of DAIMs 192(1)-192(3) are provided as anon-limiting example and for the convenience of discussion.

With reference to FIG. 5A, the DAIM 192(1) has a logically configureddownstream DAIM 192(2), but has no logically configured upstream DAIMsince the DAIM 192(1) is the first DAIM among the plurality of DAIMs192(1)-192(3). The DAIM 192(2) has a logically configured upstream DAIM192(1) and a logically configured downstream DAIM 192(3). The DAIM192(3) has a logically configured upstream DAIM 192(2), but has nologically configured downstream DAIM since the DAIM 192(3) is the lastDAIM among the plurality of DAIMs 192(1)-192(3). The plurality of DAIMs192(1)-192(3) have a plurality of upstream digital bus interfaces198(1)-198(3) and a plurality of downstream digital bus interfaces200(1)-200(3), respectively. To provide the interconnections between theplurality of DAIMs 192(1)-192(3), a downstream digital bus interface ofa logically configured upstream DAIM is coupled to an upstream digitalbus interface of a logically configured downstream DAIM. Hence, in thenon-limiting example provided herein, the DAIM 192(1) is logicallyconfigured as an upstream DAIM to the DAIM 192(2). As such, a downstreamdigital bus interface 200(1) in the DAIM 192(1) is coupled to anupstream digital bus interface 198(2) in the DAIM 192(2). The DAIM192(3) is logically configured as a downstream DAIM to the DAIM 192(3).As such, a downstream digital bus interface 200(2) in the DAIM 192(2) iscoupled to an upstream digital bus interface 198(3) in the DAIM 192(3).

With continuing reference to FIG. 5A, the DAIM 192(1) receives adownlink communications signal 196(1) via an analog communicationsinterface 202(1). The DAIM 192(1) converts the downlink communicationssignal 196(1) into downlink digital RF signals 196(1)(1), 196(1)(2) andprovides the downlink digital RF signals 196(1)(1), 196(1)(2) to theinterconnection digital bus 193 via the downstream digital bus interface200(1). The DAIM 192(2) receives the downlink communications signal196(2) via a digital communications interface 204(2). The DAIM 192(2)converts the downlink communications signal 196(2) into downlink digitalRF signal 196(2)(1) and provides the downlink digital RF signal196(2)(1) to the interconnection digital bus 193 via the upstreamdigital bus interface 198(2) and the downstream digital bus interface200(2). The DAIM 192(3) receives the downlink communications signal196(3) via an analog communications interface 202(3). The DAIM 192(3)converts the downlink communications signal 196(3) into downlink digitalRF signals 196(3)(1), 196(3)(2) and provides the downlink digital RFsignals 196(3)(1), 196(3)(2) to the interconnection digital bus 193 viathe upstream digital bus interface 198(3). As a result, the downlinkdigital RF signals 196(1)(1), 196(1)(2), 196(2)(1), 196(3)(1), 196(3)(2)are made available to the DAIMs 192(1)-192(3) through theinterconnection digital bus 193 in the main HEU 190. As previouslydiscussed in FIG. 3, a respective digital signal processing controller(not shown) in each of the DAIMs 192(1)-192(3) can programmablydetermine which downlink digital RF signal(s) among the downlink digitalRF signals 196(1)(1), 196(1)(2), 196(2)(1), 196(3)(1), 196(3)(2) isrelated to the respective DAIM and included in a plurality of combineddownlink digital RF signals 206(1)-206(3), respectively.

FIG. 5B is a schematic diagram of an exemplary main HEU 190(1)comprising the plurality of DAIMs 192(1)-192(3) in FIG. 5A that areinterconnected to the interconnection digital bus 193 via the pluralityof digital bus interfaces 194(1)-194(3) in FIG. 5A and configured toshare a plurality of combined uplink communications signals208(1)-208(3). Common elements between FIGS. 5A and 5B are shown thereinwith common element numbers, thus will not be re-described herein.

With reference to FIG. 5B, the DAIM 192(1) receives the combined uplinkcommunications signal 208(1) via at least one digital remotedistribution interface 210(1). The DAIM 192(1) converts the combineduplink communications signal 208(1) into uplink digital RF signals208(1)(1), 208(1)(2) and provides the uplink digital RF signals208(1)(1), 208(1)(2) to the interconnection digital bus 193 via thedownstream digital bus interface 200(1). The DAIM 192(2) receives thecombined uplink communications signal 208(2) via at least one digitalremote distribution interface 210(2). The DAIM 192(2) converts thecombined uplink communications signal 208(2) into uplink digital RFsignal 208(2)(1) and provides the uplink digital RF signal 208(2)(1) tothe interconnection digital bus 193 via the upstream digital businterface 198(2) and the downstream digital bus interface 200(2). TheDAIM 192(3) receives the combined uplink communications signal 208(3)via at least one digital remote distribution interface 210(3). The DAIM192(3) converts the combined uplink communications signal 208(3) intouplink digital RF signals 208(3)(1), 208(3)(2) and provides the uplinkdigital RF signals 208(3)(1), 208(3)(2) to the interconnection digitalbus 193 via the upstream digital bus interface 198(3). As a result, theuplink digital RF signals 208(1)(1), 208(1)(2), 208(2)(1), 208(3)(1),208(3)(2) are made available to the plurality of DAIMs 192(1)-192(3)through the interconnection digital bus 193 in the main HEU 190(1). Aspreviously discussed in FIG. 5A, the respective digital signalprocessing controller (not shown) in each of the DAIMs 192(1)-192(3) canprogrammably determine which uplink digital RF signal(s) among theuplink digital RF signals 208(1)(1), 208(1)(2), 208(2)(1), 208(3)(1),208(3)(2) is related to the respective DAIM and included in a pluralityof combined uplink communications signals 212(1)-212(3), respectively.

As previously discussed in FIGS. 3 and 4 above, the DAIM 120 and the DIM189 are designed to retrofit into the chassis of the main HEU 38 and theplurality of remote HEUs 84(1)-84(N) in the wide-area analog DAS 30 ofFIG. 2 for distributing the analog and/or digital communications signalsin the wide-area in the wide-area analog DAS 30. By reconfiguring themain HEU 38 and the plurality of remote HEUs 84(1)-84(N) with the DAIM120 and/or the DIM 189, it is possible to flexibly reconfigure thewide-area analog DAS 30 to distribute digital and/or analogcommunications signals over digital communications mediums.

In this regard, FIG. 6 is a schematic diagram of an exemplary opticalfiber-based wide-area DAS 220 configured to distribute digital andanalog communications signals from a main HEU 222 to one or more remoteHEUs 224(1)-224(N) over optical fiber-based digital communicationsmediums 226(1)-226(N). The main HEU 222 is reconfigured by retrofittingone or more of the DAIMs 120 illustrated FIG. 3 into the existingchassis of the main HEU 38 in FIG. 2. Elements in FIG. 2 are referencedin connection with FIG. 6 and will not be re-described herein. Commonelements between FIGS. 3, 4, and 6 are shown therein with common elementnumbers, thus will not be re-described herein.

With reference to FIG. 6, the optical fiber-based wide-area DAS 220comprises a main DAS 228 that comprises the main HEU 222. The opticalfiber-based wide-area DAS 220 further comprises one or more remote DASs230(1)-230(N) that comprise the one or more remote HEUs 224(1)-224(N),respectively. The main HEU 222 comprises one or more DAIMs232(1)-232(N), wherein each of the one or more DAIMs 232(1)-232(N) issame as the DAIM 120. The one or more DAIMs 232(1)-232(N) are configuredto distribute digital and analog communications signals to the one ormore remote HEUs 224(1)-224(N) over the optical fiber-based digitalcommunications mediums 226(1)-226(N), respectively. The opticalfiber-based digital communications mediums 226(1)-226(N) compriseoptical fiber-based downlink digital communications mediums234(1)-234(N) and optical fiber-based uplink digital communicationsmediums 236(1)-236(N), respectively. Hence, the one or more DAIMs232(1)-232(N) are configured to distribute digital and analogcommunications signals to the one or more remote HEUs 224(1)-224(N) overthe optical fiber-based downlink digital communications mediums234(1)-234(N) and the optical fiber-based uplink digital communicationsmediums 236(1)-236(N), respectively. Further, the one or more DAIMs232(1)-232(N) are coupled to one or more BTSs 238(1)-238(N) and to oneor more BBUs 240(1)-240(N), respectively. In addition, the one or moreDAIMs 232(1)-232(N) may also be coupled to one or more RAUs242(1)-242(N), respectively. For the convenience of discussion, the DAIM232(1) in the main HEU 222 and the remote HEU 224(1) are describedhereinafter as a non-limiting example. Nonetheless, the configurationand operating principles for distributing digital and analogcommunications signals in the optical fiber-based wide-area DAS 220 areapplicable to any of the one or more DAIMs 232(1)-232(N) and any of theone or more remote HEUs 224(1)-224(N).

With continuing reference to FIG. 6, like the DAIM 120, the DAIM 232(1)comprises the analog communications interface 122, the upstream digitalbus interface 128, the downstream digital bus interface 130, the atleast one digital remote distribution interface 132, the analog localdistribution interface 134, and the digital communications interface136. In a non-limiting example, the analog communications interface 122and the digital communications interface 136 are coupled to the BTS238(1) and the BBU 240(1), respectively. The analog local distributioninterface 134 may be coupled with the RAU 242(1). The digital remotedistribution interface 132 is coupled to the respective opticalfiber-based downlink digital communications medium 234(1) via arespective E/O converter 244(1) and is coupled to the respective opticalfiber-based uplink digital communications medium 236(1) via a respectiveO/E converter 246(1). The upstream digital bus interface 128 is coupledto a downstream digital bus interface (a second downstream digital businterface) (not shown) in a second DAIM (not shown) among the one ormore DAIMs 232(1)-232(N) that is logically configured as an upstreamDAIM to the DAIM 232(1). The downstream digital bus interface 130 iscoupled to an upstream digital bus interface (a third upstream digitalbus interface) (not shown) in a third DAIM among the one or more DAIMs232(1)-232(N) that is logically configured as a downstream DAIM to theDAIM 232(1). The DAIM 232(1) generates a combined downlink digital RFsignal 248(1), which is subsequently converted into a combined downlinkoptical RF signal 250(1) and distributed to the remote HEU 224(1) overthe optical fiber-based downlink digital communications medium 234(1).

With continuing reference to FIG. 6, the remote HEU 224(1) comprises oneor more remote-HEU DIMs 252(1)(1)-252(1)(M) corresponding to one or moreRF bands (not shown), respectively. Each of the one or more remote-HEUDIMs 252(1)(1)-252(1)(M) is same as the DIM 189. In this regard, each ofthe one or more remote-HEU DIMs 252(1)(1)-252(1)(M) comprises theupstream digital bus interface (remote-DIM upstream digital businterface) 128, the downstream digital bus interface (remote-DIMdownstream digital bus interface) 130, the at least one digital remotedistribution interface (at least one remote-DIM digital remotedistribution interface) 132, the analog local distribution interface(remote-DIM analog local distribution interface) 134, and the digitalcommunications interface (remote-DIM digital communications interface)136. At least one remote-HEU DIM among the one or more remote-HEU DIMs252(1)(1)-252(1)(M) in the remote HEU 224(1) is configured to interfacewith the DAIM 232(1) in the main HEU 222. For the convenience ofdiscussion, the remote-HEU DIM 252(1)(M) is referenced herein as the atleast one remote-HEU DIM configured to interface with the DAIM 232(1) inthe main HEU 222 in a non-limiting example.

With continuing reference to FIG. 6, the remote-DIM digital remotedistribution interface 132 in the remote-HEU DIM 252(1)(M) is coupled tothe optical fiber-based downlink digital communications medium 234(1)via a remote-HEU O/E converter 254(1) and to the optical fiber-baseduplink digital communications medium 236(1) via a remote-HEU E/Oconverter 256(1). The remote-HEU O/E converter 254(1) receives andconverts the combined downlink optical RF signal 250(1) back to thecombined downlink digital RF signal 248(1). The remote-HEU DIM 252(1)(M)receives the combined downlink digital RF signal 248(1) from theremote-DIM digital remote distribution interface 132 in the remote-HEUDIM 252(1)(M). Subsequently, remote-HEU DIM 252(1)(M) converts thecombined downlink digital RF signal 248(1) into one or more firstremote-DIM downlink digital RF signals 258 that correspond to the one ormore RF bands. The remote-HEU DIM 252(1)(M) then provides the one ormore first remote-DIM downlink digital RF signals 258 to the remote-DIMupstream digital bus interface 128 and the remote-DIM downstream digitalbus interface 130. The remote-HEU DIM 252(1)(M) may receive one or moresecond remote-DIM downlink digital RF signals 260 corresponding to theone or more RF bands from the remote-DIM upstream digital bus interface128. The remote-HEU DIM 252(1)(M) may also receive one or more thirdremote-DIM downlink digital RF signals 262 corresponding to the one ormore RF bands from the remote-DIM downstream digital bus interface 130.The remote-HEU DIM 252(1)(M) is configured to provide the one or moresecond remote-DIM downlink digital RF signals 260 to the remote-DIMdownstream digital bus interface 130. The remote-HEU DIM 252(1)(M) isalso configured to provide the one or more third remote-DIM downlinkdigital RF signals 262 to the remote-DIM upstream digital bus interface128. The remote-HEU DIM 252(1)(M) may also receive a remote-DAS downlinkdigital baseband signal 264(M) from a remote-DAS digital signal source266(1)(M). In a non-limiting example, the remote-DAS digital signalsource 266(1)(M) is a BBU. The remote-HEU DIM 252(1)(M) converts theremote-DAS downlink digital baseband signal 264(M) to generate one ormore fourth remote-DIM downlink digital RF signals 268 corresponding tothe one or more RF bands. The remote-HEU DIM 252(1)(M) provides the oneor more fourth remote-DIM downlink digital RF signals 268 to theremote-DIM upstream digital bus interface 128 and the remote-DIMdownstream digital bus interface 130.

With continuing reference to FIG. 6, the remote-HEU DIM 252(1)(M) isfurther configured to combine one or more remote-DIM downlink digitalsignals (not shown) to generate a remote-DIM combined downlink digitalRF signal (not shown), which is then converted into a remote-DIMcombined downlink analog RF signal 270(M) by a remote-DIM D/A converter(not shown) in the remote-HEU DIM 252(1)(M). The remote-DIM combineddownlink digital RF signal and the remote-DIM combined downlink analogRF signal 270(M) correspond to an RF band associated with the remote-HEUDIM 252(1)(M) among the one or more RF bands supported by the remote HEU224(1). The remote-DIM combined downlink analog RF signal 270(M) isprovided to the remote-DIM analog local distribution interface 134. Theone or more remote-DIM downlink digital signals are programmablydetermined by a remote-DIM digital signal processing controller (notshown) in the remote-HEU DIM 252(1)(M).

With continuing reference to FIG. 6, a remote-HEU RF combiner/splitter272(1) in the remote HEU 224(1) converts and combines one or moreremote-DIM combined downlink analog RF signals 270(1)-270(M) to generatea remote-HEU combined downlink analog RF signal 274(1). An remote-HEUoptical splitter/combiner 276(1) then splits the remote-HEU combineddownlink analog RF signal 274(1) to generate one or more remote-OIMdownlink analog RF signals 278(1)-278(P), which are subsequentlyreceived by one or more remote-HEU OIMs 280(1)(1)-280(1)(P). The one ormore remote-HEU OIMs 280(1)(1)-280(1)(P) then convert the one or moreremote-OIM downlink analog RF signals 278(1)-278(P) into one or moreremote-OIM downlink optical RF signals 282(1)-282(P) and provide to theone or more remote-DAS RAUs 284(1)(1)-284(1)(P), respectively.

With continuing reference to FIG. 6, the one or more remote-HEU OIMs280(1)(1)-280(1)(P) receive one or more remote-OIM uplink optical RFsignals 286(1)-286(P). The one or more remote-HEU OIMs280(1)(1)-280(1)(P) then convert the one or more remote-OIM uplinkoptical RF signals 286(1)-286(P) into one or more remote-OIM uplinkanalog RF signals 288(1)-288(P). The remote-HEU opticalsplitter/combiner 276(1) combines the one or more remote-OIM uplinkanalog RF signals 288(1)-288(P) to generate a remote-HEU combined uplinkanalog RF signal 290(1). The remote-HEU RF combiner/splitter 272(1) thensplits the remote-HEU combined uplink analog RF signal 290(1) into oneor more remote-DIM combined uplink analog RF signals 292(1)-292(M)corresponding to the one or more RF bands, respectively. The one or moreremote-DIM combined uplink analog RF signals 292(1)-292(M) are receivedby the one or more remote-HEU DIMS 252(1)(1)-252(1)(M), respectively.The remote-HEU DIM 252(1)(M) receives the remote-DIM combined uplinkanalog RF signal 292(M) among the one or more remote-DIM combined uplinkanalog RF signals 292(1)-292(M). A remote-DIM A/D converter (not shown)inside the remote-HEU DIM 252(1)(M) receives the remote-DIM combineduplink analog RF signal 292(M) from the remote-DIM analog localdistribution interface 134 and converts the remote-DIM combined uplinkanalog RF signal 292(M) into a remote-DIM combined uplink digital RFsignal (not shown). The digital signal processing circuit 152 (notshown) in the remote-HEU DIM 252(1)(M) (the remote-DIM digital signalprocessing circuit) splits the remote-DIM combined uplink digital RFsignal into one or more first remote-DIM uplink digital RF signals 294and provides the one or more first remote-DIM uplink digital RF signals294 to the remote-DIM upstream digital bus interface 128 and theremote-DIM downstream digital bus interface 130.

With continuing reference to FIG. 6, the remote-HEU DIM 252(1)(M) mayreceive one or more second remote-DIM uplink digital RF signals 296 andone or more third remote-DIM uplink digital RF signals 298 from theremote-DIM upstream digital bus interface 128 and the remote-DIMdownstream digital bus interface 130, respectively. The remote-HEU DIM252(1)(M) is configured to provide the one or more second remote-DIMuplink digital RF signals 296 to the remote-DIM downstream digital businterface 130. The remote-HEU DIM 252(1)(M) is also configured toprovide the one or more third remote-DIM uplink digital RF signals 298to the remote-DIM upstream digital bus interface 128. The remote-HEU DIM252(1)(M) may also receive a remote-DAS uplink digital baseband signal300(M) from the remote-DIM digital communications interface 136 that iscoupled to the remote-DAS digital signal source 266(1)(M). Theremote-HEU DIM 252(1)(M) converts the remote-DAS uplink digital basebandsignal 300(M) to generate one or more fourth remote-DIM uplink digitalRF signals 302. The remote-HEU DIM 252(1)(M) provides the one or morefourth remote-DIM uplink digital RF signals 302 to the remote-DIMupstream digital bus interface 128 and the remote-DIM downstream digitalbus interface 130.

With continuing reference to FIG. 6, the remote-HEU DIM 252(1)(M)combines one or more remote-DIM uplink digital RF signals (not shown) togenerate a combined uplink digital RF signal 304(1). The one or moreremote-DIM uplink digital RF signals are programmably determined by theremote-DIM digital signal processing controller 156 (not shown) from theone or more first remote-DIM uplink digital RF signals, the one or moresecond remote-DIM uplink digital signals, the one or more thirdremote-DIM uplink digital signals, and the one or more fourth remote-DIMuplink digital signals. The combined uplink digital RF signal 304(1) issubsequently converted into a combined uplink optical RF signal 306(1)by the remote-HEU E/O converter 256(1) and distributed to the respectiveO/E converter 246(1) via the respective optical fiber-based uplinkdigital communications medium 236(1). The respective O/E converter246(1) converts the combined uplink optical RF signal 306(1) back to thecombined uplink digital RF signal 304(1) and provides to the at leastone digital remote distribution interface 132 in the DAIM 232(1).

FIG. 7 is a flowchart of an exemplary HEU configuration process 310 forreconfiguring the main HEU 38 in FIG. 2 with the one or more DAIMs231(1)-232(N) in FIG. 6. Elements in FIGS. 2, 3, and 6 are referenced inconnection to FIG. 7 and will not be re-described herein.

According to the HEU configuration process 310, the one or more main-HEURIMs 44(1)-44(M) in the main HEU 38 are replaced with the one or moreDAIMs 232(1)-232(N) (block 312). Next, the HEU configuration process 310configures each of the one or more DAIMs 232(1)-232(N) (block 314). Fora DAIM among the one or more DAIMs 232(1)-232(N), an analogcommunications interface (122) is coupled to a respective BTS among theone or more BTSs 238(1)-238(N) (block 316). Next, a digitalcommunications interface 136 in the DAIM is coupled to a respective BBUamong the one or more BBUs 240(1)-240(N) (block 318). Subsequently, atleast one digital remote distribution interface 132 in the DAIM iscoupled to a respective optical fiber-based downlink digitalcommunications medium 234 and a respective optical fiber-based uplinkdigital communications medium 236 (block 320). Then, an analog localdistribution interface 134 in the DAIM is coupled to a respective RAUamong the one or more RAUs 242(1)-242(N) (block 322). To enableinterconnections between the one or more DAIMs 232(1)-232(N), a logicalupstream DAIM and a logical downstream DAIM are identified for each ofthe one or more DAIMs 232(1)-232(N). Subsequently for each of the DAIMamong the one or more DAIMs 232(1)-232(N), the upstream digital businterface 128 of the DAIM is coupled to a downstream digital bus 130 ofthe logical upstream DAIM. Also, the downstream digital bus interface130 of the DAIM is coupled to an upstream digital bus interface 128 ofthe logical downstream DAIM.

Alternative to retrofitting the one or more DAIMs 120 of FIG. 3 into theexisting chassis of the main HEU 38 in FIG. 2, it is also possible toretrofit one or more DIMs 189 of FIG. 4 into the existing chassis of themain-HEU DAS-OIU 42 in FIG. 2 for distributing digital and analogcommunications signals over optical fiber-based digital communicationsmediums. In this regard, FIG. 8 is a schematic diagram of an exemplaryoptical fiber-based wide-area DAS 220(1) configured to distributedigital and analog communications signals from a main HEU 222(1) to theone or more remote HEUs 224(1)-224(N) in FIG. 6 over the opticalfiber-based digital communications mediums 226(1)-226(N) in FIG. 6,wherein the main HEU 222(1) is reconfigured by retrofitting one or moreof the DIMs 189 illustrated in FIG. 4 into the existing chassis of themain HEU 38 in FIG. 2. Common elements between FIGS. 2, 4, 6, and 8 areshown therein with common element numbers, thus will not be re-describedherein.

With reference to FIG. 8, the optical fiber-based wide-area DAS 220(1)comprises a main DAS 228(1) that comprises the main HEU 222(1). Theoptical fiber-based wide-area DAS 220(1) further comprises the one ormore remote DASs 230(1)-230(N) that comprise the one or more remote HEUs224(1)-224(N), respectively. In the main HEU 222(1), one or more DIMs(main-HEU DIMs) 330(1)-330(N) are retrofit into the chassis of amain-HEU DAS-OIU 42(1). The one or more DIMs 330(1)-330(N) areconfigured to distribute digital and analog communications signals tothe one or more remote HEUs 224(1)-224(N) over the optical fiber-baseddigital communications mediums 226(1)-226(N), respectively. The opticalfiber-based digital communications mediums 226(1)-226(N) comprise theoptical fiber-based downlink digital communications mediums234(1)-234(N) and the optical fiber-based uplink digital communicationsmediums 236(1)-236(N), respectively. Hence, the one or more main-HEUDIMs 330(1)-330(N) are configured to distribute digital and analogcommunications signals to the one or more remote HEUs 224(1)-224(N) overthe optical fiber-based downlink digital communications mediums234(1)-234(N) and the optical fiber-based uplink digital communicationsmediums 236(1)-236(N), respectively. For the convenience of discussion,the main-HEU DIM 330(1) in the main HEU 222(1) and the remote HEU 224(1)are described hereinafter as a non-limiting example. Nonetheless, theconfiguration and operating principles for distributing digital andanalog communications signals in the optical fiber-based wide-area DAS220(1) are applicable to any of the one or more main-HEU DIMs330(1)-330(N) and any of the one or more remote HEUs 224(1)-224(N).

With continuing reference to FIG. 8, the main-HEU DIM 330(1) among theone or more main-HEU DIMs 330(1)-330(N) receives the second downlinkanalog RF signal 60(1) among the plurality of second downlink analog RFsignals 60(1)-60(N) from the optical splitter/combiner 58. The seconddownlink analog RF signal (downlink analog RF signal) 60(1) is receivedby the main-HEU DIM 330(1) via the analog local distribution interface134. The A/D converter 148 (not shown) in the main-HEU DIM 330(1)converts the second downlink analog RF signal 60(1) to generate adownlink digital RF signal 150 (not shown). The digital signalprocessing circuit 152 (not shown) in the main-HEU DIM 330(1) receivesand converts the downlink digital RF signal 150 to generate one or morefirst downlink digital RF signals 332. The main-HEU DIM 330(1) thenprovides the one or more first downlink digital RF signals 332 to theupstream digital bus interface 128 and the downstream digital businterface 130 for sharing the one or more first downlink digital RFsignals 332 with the rest of main-HEU DIMs 330(1)-330(N) in the main HEU222(1). The digital signal processing circuit 152 in the main-HEU DIM330(1) may also receive one or more second downlink digital RF signals334 from the upstream digital bus interface 128 and one or more thirddownlink digital RF signals 336 from the downstream digital businterface 130. In turn, the digital signal processing circuit 152 in themain-HEU DIM 330(1) provides the one or more second downlink digital RFsignals 334 to the downstream digital bus interface 130 and provides theone or more third downlink digital RF signals 336 to the upstreamdigital bus interface 128. The one or more main-HEU DIMs 330(1)-330(N)may be coupled to one or more BBUs 340(1)-340(N), respectively. In thisregard, the digital signal processing circuit 152 in the main-HEU DIM330(1) may also receive a downlink digital baseband signal 338 from thedigital communications interface 136, which is coupled to the BBU340(1). In a non-limiting example, the downlink digital baseband signal338 is in conformance with the CPRI format. The digital signalprocessing circuit 152 in the main-HEU DIM 330(1) converts the downlinkdigital baseband signal 338 to generate one or more fourth downlinkdigital RF signals 342. Again, the digital signal processing circuit 152in the main-HEU DIM 330(1) provides the one or more fourth downlinkdigital RF signals 342 to the upstream digital bus interface 128 and thedownstream digital bus interface 130.

With continuing reference to FIG. 8, the digital signal processingcircuit 152 in the main-HEU DIM 330(1) combines one or more respectivefirst downlink digital RF signals (not shown), one or more respectivesecond downlink digital RF signals (not shown), one or more respectivethird downlink digital RF signals (not shown), and one or morerespective fourth downlink digital RF signals (not shown) into thecombined downlink digital RF signal 248(1). The one or more respectivefirst downlink digital RF signals are programmably determined by thedigital signal processing controller 156 (not shown) among the one ormore first downlink digital RF signals 332. The one or more respectivesecond downlink digital RF signals are programmably determined by thedigital signal processing controller 156 among the one or more seconddownlink digital RF signals 334. The one or more respective thirddownlink digital RF signals are programmably determined by the digitalsignal processing controller 156 among the one or more third downlinkdigital RF signals 336. The one or more respective fourth downlinkdigital RF signals are programmably determined by the digital signalprocessing controller 156 among the one or more fourth downlink digitalRF signals 342. The combined downlink digital RF signal 248(1) is thenprovided to the respective E/O converter 244(1) for distribution to theremote HEU 224(1). The signal processing performed by the remote HEU224(1) has been described previously in reference to FIG. 6 and will notbe re-described herein.

With continuing reference to FIG. 8, the digital signal processingcircuit 152 in the main-HEU DIM 330(1) receives the combined uplinkdigital RF signal 304(1) from the remote HEU 224(1) via the respectiveO/E converter 246(1) that is coupled to the at least one digital remotedistribution interface 136. The digital signal processing circuit 152 inthe main-HEU DIM 330(1) splits the combined uplink digital RF signal304(1) to generate one or more first uplink digital RF signals 344. Themain-HEU DIM 330(1) then provides the one or more first uplink digitalRF signals 344 to the upstream digital bus interface 128 and thedownstream digital bus interface 130 for sharing the one or more firstuplink digital RF signals 344 with the rest of main-HEU DIMS330(1)-330(N) in the main HEU 222(1). The digital signal processingcircuit 152 in the main-HEU DIM 330(1) may also receive one or moresecond uplink digital RF signals 346 from the upstream digital businterface 128 and one or more third uplink digital RF signals 348 fromthe downstream digital bus interface 130. In turn, the digital signalprocessing circuit 152 in the main-HEU DIM 330(1) provides the one ormore second uplink digital RF signals 346 to the downstream digital businterface 130 and provides the one or more third uplink digital RFsignals 348 to the upstream digital bus interface 128. The digitalsignal processing circuit 152 in the main-HEU DIM 330(1) may alsoreceive an uplink digital baseband signal 350 from the digitalcommunications interface 136, which is coupled to the BBU 340(1). In anon-limiting example, the uplink digital baseband signal 350 is inconformance with the CPRI format. The digital signal processing circuit152 in the main-HEU DIM 330(1) converts the uplink digital basebandsignal 350 to generate one or more fourth uplink digital RF signals 352.Again, the digital signal processing circuit 152 in the main-HEU DIM330(1) provides the one or more fourth uplink digital RF signals 352 tothe upstream digital bus interface 128 and the downstream digital businterface 130.

With continuing reference to FIG. 8, the digital signal processingcircuit 152 in the main-HEU DIM 330(1) combines one or more respectivefirst uplink digital RF signals (not shown), one or more respectivesecond uplink digital RF signals (not shown), one or more respectivethird uplink digital RF signals (not shown), and one or more respectivefourth uplink digital RF signals (not shown) into the second uplinkdigital RF signal (the uplink digital RF signal) 72(1). The one or morerespective first uplink digital RF signals are programmably determinedby the digital signal processing controller 156 among the one or morefirst uplink digital RF signals 344. The one or more respective seconduplink digital RF signals are programmably determined by the digitalsignal processing controller 156 among the one or more second uplinkdigital RF signals 346. The one or more respective third uplink digitalRF signals are programmably determined by the digital signal processingcontroller 156 among the one or more third uplink digital RF signals348. The one or more respective fourth uplink digital RF signals areprogrammably determined by the digital signal processing controller 156among the one or more fourth uplink digital RF signals 352. The seconduplink digital RF signal 74 is then provided to the opticalsplitter/combiner 58.

FIG. 9 is a flowchart of an exemplary HEU configuration process 360 forreconfiguring the main HEU 38 in FIG. 2 with the one or more main-HEUDIMs 330(1)-330(N) in FIG. 8. Elements in FIGS. 2, 3, 6, and 8 arereferenced in connection to FIG. 9 and will not be re-described herein.

According to the HEU configuration process 360, the plurality of OIMs62(1)-62(N) in the main HEU 38 are replaced with the one or moremain-HEU DIMs 330(1)-330(N) (block 362). Next, the HEU configurationprocess 310 configures each of the one or more main-HEU DIMs330(1)-330(N) (block 364). For a main-HEU DIM among the one or moremain-HEU DIMs 330(1)-330(N), a digital communications interface 136 inthe main-HEU DIM is coupled to a respective BBU among the one or moreBBUs 340(1)-340(N) (block 366). Subsequently, at least one digitalremote distribution interface 132 in the main-HEU DIM is coupled to arespective optical fiber-based downlink digital communications medium234 and a respective optical fiber-based uplink digital communicationsmedium 236 (block 368). Then, an analog local distribution interface 134in the main-HEU DIM is coupled to a respective RIM among the one or moremain-HEU RIMs 44(1)-44(N) (block 370). To enable interconnectionsbetween the one or more main-HEU DIMs 330(1)-330(N), a logical upstreammain-HEU DIM and a logical downstream main-HEU DIM are identified foreach of the one or more main-HEU DIMs 330(1)-330(N). Subsequently foreach of the main-HEU DIM among the one or more main-HEU DIMs330(1)-330(N), the upstream digital bus interface 128 of the main-HEUDIM is coupled to a downstream digital bus 130 of the logical upstreammain-HEU DIM. Also, the downstream digital bus interface 130 of themain-HEU DIM is coupled to an upstream digital bus interface 128 of thelogical downstream main-HEU DIM.

As previously discussed in references to FIGS. 6 and 8, the combineddownlink digital RF signal 248(1) comprises the one or more respectivefirst downlink digital RF signals, the one or more respective seconddownlink digital RF signals, the one or more respective third downlinkdigital RF signals, and the one or more respective fourth downlinkdigital RF signals. Likewise, the combined uplink digital RF signal304(1) comprises the one or more respective first uplink digital RFsignals, the one or more respective second uplink digital RF signals,the one or more respective third uplink digital RF signals, and the oneor more respective fourth uplink digital RF signals. As such, theoptical fiber-based downlink digital communications mediums 234(1) andthe optical fiber-based uplink digital communications mediums 236(1) arerequired to provide larger bandwidth, thus increasing complexities andcosts of the respective E/O converters 244(1), the respective O/Econverters 246(1), the remote-HEU O/E converter 254(1), and theremote-HEU E/O converter 256(1). In this regard, FIG. 10 is a schematicdiagram of an exemplary DAS 380 comprising a main HEU 382 coupled to aremote HEU 384 over a plurality of respective optical fiber-baseddownlink communications mediums 386(1)-386(Q) and a plurality ofrespective optical fiber-based uplink communications mediums387(1)-387(Q).

With reference to FIG. 10, the main HEU 382 comprises a DAIM 388 or aDIM 390. The DAIM 388 or the DIM 390 comprises a plurality of digitalremote distribution interfaces 392(1)-392(Q) that are coupled to aplurality of main-HEU E/O converters 394(1)-394(Q) and a plurality ofmain-HEU O/E converters 396(1)-396(Q), respectively. The remote HEU 384comprises a remote-HEU DIM 398. The remote-HEU DIM 398 comprises aplurality of remote-DIM digital remote distribution interfaces400(1)-400(Q). The plurality of remote-DIM digital remote distributioninterfaces 400(1)-400(Q) are coupled to a plurality of remote-HEU O/Econverters 402(1)-402(Q) and a plurality of remote-HEU E/O converters404(1)-404(Q), respectively. The plurality of main-HEU E/O converters394(1)-394(Q) is coupled to the plurality of remote-HEU O/E converters402(1)-402(Q) over the plurality of respective optical fiber-baseddownlink communications mediums 386(1)-386(Q), respectively. Theplurality of main-HEU O/E converters 396(1)-396(Q) is coupled to theplurality of remote-HEU E/O converters 404(1)-404(Q) over the pluralityof respective optical fiber-based uplink communications mediums387(1)-387(Q), respectively.

With continuing reference to FIG. 10, a digital signal processingcircuit (not shown) in the DAIM 388 or the DIM 390 splits a combineddownlink digital RF signal (not shown) into a plurality ofbandwidth-reduced combined downlink digital RF signals 406(1)-406(Q).The plurality of bandwidth-reduced combined downlink digital RF signals406(1)-406(Q) is distributed to the remote HEU 384 via the plurality ofdigital remote distribution interfaces 392(1)-392(Q). Similarly, adigital signal processing circuit (not shown) in the remote-HEU DIM 398splits a combined uplink digital RF signal (not shown) into a pluralityof bandwidth-reduced combined uplink digital RF signals 408(1)-408(Q).The plurality of bandwidth-reduced combined uplink digital RF signals408(1)-408(Q) is distributed to the main HEU 382 via the plurality ofremote-DIM digital remote distribution interfaces 400(1)-400(Q).

By providing the plurality of digital remote distribution interfaces392(1)-392(Q) in the main HEU 382 and the plurality of remote-DIMdigital remote distribution interfaces 400(1)-400(Q) in the remote HEU384, it is possible to provide the plurality of main-HEU E/O converters394(1)-394(Q), the plurality of main-HEU O/E converters 396(1)-396(Q),the plurality of remote-HEU O/E converters 402(1)-402(Q), and theplurality of remote-HEU E/O converters 404(1)-404(Q) with reducedcomplexities and costs. However, it may be desirable to combine theplurality of optical fiber-based communications mediums 386(1)-386(Q)into a single optical fiber-based communications medium to achievefurther cost savings. In this regard, FIG. 11 is a schematic diagram ofan exemplary DAS 380(1) comprising a main HEU 382(1) coupled to a remoteHEU 384(1) using wavelength-division multiplexing (WDM). Common elementsbetween FIGS. 10 and 11 are shown therein with common element numbers,thus will not be re-described herein.

With reference to FIG. 11, the main HEU 382(1) comprises a main-HEU WDMcircuit 410 that is coupled to a remote-HEU WDM circuit 412 comprised inthe remote HEU 384(1) over an optical fiber-based digital communicationsmedium 414. In the main HEU 382(1), the plurality of main-HEU E/Oconverters 394(1)-394(Q) converts the plurality of bandwidth-reducedcombined downlink digital RF signals 406(1)-406(Q) into a plurality ofbandwidth-reduced combined downlink optical RF signals 416(1)-416(Q).The main-HEU WDM circuit 410 wavelength multiplexes the plurality ofbandwidth-reduced combined downlink optical RF signals 416(1)-416(Q) togenerate a combined downlink optical RF signal 418. The remote-HEU WDMcircuit 412 in turn wavelength de-multiplexes the combined downlinkoptical RF signal 418 back into the plurality of bandwidth-reducedcombined downlink optical RF signals 416(1)-416(Q). The plurality ofremote-HEU O/E converters 402(1)-402(Q) subsequently convert theplurality of bandwidth-reduced combined downlink optical RF signals416(1)-416(Q) into the plurality of bandwidth-reduced combined downlinkdigital RF signals 406(1)-406(Q).

With continuing reference to FIG. 11, in the remote HEU 384(1), theplurality of remote-HEU E/O converters 404(1)-404(Q) converts theplurality of bandwidth-reduced combined uplink digital RF signals408(1)-408(Q) into a plurality of bandwidth-reduced combined uplinkoptical RF signals 420(1)-420(Q). The remote-HEU WDM circuit 412wavelength multiplexes the plurality of bandwidth-reduced combineduplink optical RF signals 420(1)-420(Q) to generate a combined uplinkoptical RF signal 422. The main-HEU WDM circuit 410 in turn wavelengthde-multiplexes the combined uplink optical RF signal 422 back into theplurality of bandwidth-reduced combined uplink optical RF signals420(1)-420(Q). The plurality of main-HEU O/E converters 396(1)-396(Q)subsequently converts the plurality of bandwidth-reduced combined uplinkoptical RF signals 420(1)-420(Q) into the plurality of bandwidth-reducedcombined uplink digital RF signals 408(1)-408(Q).

Alternative to adding the plurality of digital remote distributioninterfaces 392(1)-392(Q) in the DAIM 388 or the DIM 390 and theplurality of remote-DIM digital remote distribution interfaces400(1)-400(Q) in the remote-HEU DIM 398 in FIG. 10, it is also possibleto utilize multiple DAIMs and/or DIMs for digital and/or analogcommunications signals distribution between a main HEU and a remote HEU.In this regard, FIG. 12 is a schematic diagram of an exemplary DAS 430wherein a main HEU 432 and a remote HEU 434 are configured toconcurrently distribute digital and/or analog communications signalsmultiple using a plurality of DAIMs 436(1)-436(Q) and a plurality ofDIMs 438(1)-438(Q). Common elements between FIGS. 10 and 12 are showntherein with common element numbers, thus will not be re-describedherein.

With reference to FIG. 12, a main-HEU load-sharing bus 440 interconnectsthe plurality of DAIMs 436(1)-436(Q). A main-HEU load-sharing controller442, which may be incorporated into the plurality of DAIMs 436(1)-436(Q)for example, is configured to implement load sharing among the pluralityof bandwidth-reduced combined downlink digital RF signals 406(1)-406(Q).In the remote HEU 434, a remote-HEU load-sharing bus 444 interconnectsthe plurality of DIMs 438(1)-438(Q). A remote-HEU load-sharingcontroller 446, which may be incorporated into the plurality of DIMs438(1)-438(Q) for example, is configured to implement load sharing amongthe plurality of bandwidth-reduced combined uplink digital RF signals408(1)-408(Q).

Alternative to employing the plurality of optical fiber-basedcommunications mediums 386(1)-386(Q) between the main HEU 432 and theremote HEU 434, it may be desirable to combine the plurality of opticalfiber-based communications mediums 386(1)-386(Q) into a single opticalfiber-based communications medium to achieve further cost savings. Inthis regard, FIG. 13 is a schematic diagram of an exemplary DAS 430(1)wherein a main HEU 432(1) and a remote HEU 434(1) are configured toconcurrently distribute digital and/or analog communications signalsmultiple using WDM. Common elements between FIGS. 12 and 13 are showntherein with common element numbers, thus will not be re-describedherein.

With reference to FIG. 13, the main HEU 432(1) comprises a main-HEU WDMcircuit 448 that is coupled to a remote-HEU WDM circuit 450 comprised inthe remote HEU 384(1) over an optical fiber-based digital communicationsmedium 452. In the main HEU 432(1), the plurality of main-HEU E/Oconverters 394(1)-394(Q) converts the plurality of bandwidth-reducedcombined downlink digital RF signals 406(1)-406(Q) into a plurality ofbandwidth-reduced combined downlink optical RF signals 454(1)-454(Q).The main-HEU WDM circuit 448 wavelength multiplexes the plurality ofbandwidth-reduced combined downlink optical RF signals 454(1)-454(Q) togenerate a combined downlink optical RF signal 456. The remote-HEU WDMcircuit 450 in turn wavelength de-multiplexes the combined downlinkoptical RF signal 456 back into the plurality of bandwidth-reducedcombined downlink optical RF signals 454(1)-454(Q). The plurality ofremote-HEU O/E converters 402(1)-402(Q) subsequently converts theplurality of bandwidth-reduced combined downlink optical RF signals454(1)-454(Q) into the plurality of bandwidth-reduced combined downlinkdigital RF signals 406(1)-406(Q).

With continuing reference to FIG. 11, in the remote HEU 434(1), theplurality of remote-HEU E/O converters 404(1)-404(Q) converts theplurality of bandwidth-reduced combined uplink digital RF signals408(1)-408(Q) into a plurality of bandwidth-reduced combined uplinkoptical RF signals 458(1)-458(Q). The remote-HEU WDM circuit 450wavelength multiplexes the plurality of bandwidth-reduced combineduplink optical RF signals 458(1)-458(Q) to generate a combined uplinkoptical RF signal 460. The main-HEU WDM circuit 448 in turn wavelengthde-multiplexes the combined uplink optical RF signal 460 back into theplurality of bandwidth-reduced combined uplink optical RF signals458(1)-458(Q). The plurality of main-HEU O/E converters 396(1)-396(Q)subsequently converts the plurality of bandwidth-reduced combined uplinkoptical RF signals 458(1)-458(Q) into the plurality of bandwidth-reducedcombined uplink digital RF signals 408(1)-408(Q).

The DAIM 120 in FIG. 3 or the DIM 189 in FIG. 4 may be provided in ananalog DAS 470 in an indoor environment, as illustrated in FIG. 14. FIG.14 is a partially schematic cut-away diagram of an exemplary buildinginfrastructure in which the analog DAS 470, which can include the DAIM120 in FIG. 3 or the DIM 189 in FIG. 4 to support the distribution ofdigital and/or communications signals, can be employed. The buildinginfrastructure 472 in this embodiment includes a first (ground) floor474(1), a second floor 474(2), and a third floor 474(3). The floors474(1)-474(3) are serviced by a central unit 476, which may include theDAIM 120 in FIG. 3 or the DIM 189 in FIG. 4, to provide antenna coverageareas 478 in the building infrastructure 470. The central unit 476 iscommunicatively coupled to a base station 480 to receive downlinkcommunications signals 482D from the base station 480. The central unit476 is communicatively coupled to remote antenna units 484 to receiveuplink communications signals 482U from the remote antenna units 484, aspreviously discussed above. The downlink and uplink communicationssignals 482D, 482U communicated between the central unit 476 and theremote antenna units 484 are carried over a riser cable 486. The risercable 486 may be routed through interconnect units (ICUs) 488(1)-488(3)dedicated to each of the floors 474(1)-474(3) that route the downlinkand uplink communications signals 482D, 482U to the remote antenna units484 and also provide power to the remote antenna units 484 via arraycables 490.

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is no way intended thatany particular order be inferred.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the invention. Since modifications, combinations,sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A digital interface module (DIM) in a maindistributed antenna system (DAS) to support a wide-area DAS, comprising:at least one digital remote distribution interface to be coupled with aremote DAS component in a remote DAS in the wide-area DAS; an analoglocal distribution interface configured to receive a downlink analogradio frequency (RF) signal from a radio interface module (RIM) in themain DAS; a digital bus interface, comprising: an upstream digital businterface to be coupled with a second downstream digital bus interfacecomprised in a second DIM that is logically configured as an upstreamDIM to the DIM; and a downstream digital bus interface to be coupledwith a third upstream digital bus interface comprised in a third DIMthat is logically configured as a downstream DIM to the DIM; ananalog-to-digital (A/D) converter coupled to the analog localdistribution interface, wherein the A/D converter is configured to:receive the downlink analog RF signal from the analog local distributioninterface; and convert the downlink analog RF signal to generate adownlink digital RF signal; a digital signal processing circuit coupledto the A/D converter and the at least one digital remote distributioninterface; and wherein the digital signal processing circuit isconfigured to: receive the downlink digital RF signal from the A/Dconverter; convert the downlink digital RF signal to generate one ormore first downlink digital RF signals; combine one or more respectivefirst downlink digital RF signals to generate a combined downlinkdigital RF signal; and provide the combined downlink digital RF signalto the at least one digital remote distribution interface to bedistributed to the remote DAS component.
 2. The DIM of claim 1, furthercomprising a digital communications interface coupled to the digitalsignal processing circuit, the digital communications interface isconfigured to receive a downlink digital baseband signal from a digitalsignal source.
 3. The DIM of claim 2, further comprising a digitalsignal processing controller communicatively coupled to the digitalsignal processing circuit, the digital signal processing controller isconfigured to programmably determine the one or more respective firstdownlink digital RF signals among the one or more first downlink digitalRF signals to be combined into the combined downlink digital RF signal.4. The DIM of claim 3, wherein the downlink digital baseband signal isconfigured to be in compliance with a common public radio interface(CPRI) format.
 5. The DIM of claim 3, wherein the digital signalprocessing circuit is further configured to: provide the one or morefirst downlink digital RF signals to the downstream digital businterface; provide the one or more first downlink digital RF signals tothe upstream digital bus interface; receive one or more second downlinkdigital RF signals from the upstream digital bus interface; and providethe one or more second downlink digital RF signals to the downstreamdigital bus interface.
 6. The DIM of claim 5, wherein the digital signalprocessing circuit is further configured to: receive one or more thirddownlink digital RF signals from the downstream digital bus interface;provide the one or more third downlink digital RF signals to theupstream digital bus interface; and combine one or more respectivesecond downlink digital RF signals and one or more respective thirddownlink digital RF signals to generate the combined downlink digital RFsignal, wherein the one or more respective second downlink digital RFsignals and the one or more respective third downlink digital RF signalsare programmably determined by the digital signal processing controlleramong the one or more second downlink digital RF signals and the one ormore third downlink digital RF signals, respectively.
 7. The DIM ofclaim 3, wherein the digital signal processing circuit is furtherconfigured to: convert the downlink digital baseband signal to generateone or more fourth downlink digital RF signals; provide the one or morefourth downlink digital RF signals to the downstream digital businterface; provide the one or more fourth downlink digital RF signals tothe upstream digital bus interface; and combine one or more respectivefourth downlink digital RF signals to generate the combined downlinkdigital RF signal, wherein the one or more respective fourth downlinkdigital RF signals are programmably determined by the digital signalprocessing controller among the one or more fourth downlink digital RFsignals.
 8. The DIM of claim 3, wherein the digital signal processingcircuit is further configured to: receive a combined uplink digital RFsignal from the remote DAS component via the at least one digital remotedistribution interface; split the combined uplink digital RF signal togenerate one or more first uplink digital RF signals; provide the one ormore first uplink digital RF signals to the downstream digital businterface; provide the one or more first uplink digital RF signals tothe upstream digital bus interface; and combine one or more respectivefirst uplink digital RF signals to generate an uplink digital RF signal,wherein the one or more respective first uplink digital RF signals areprogrammably determined by the digital signal processing controlleramong the one or more first uplink digital RF signals.
 9. The DIM ofclaim 8, wherein the digital signal processing circuit is furtherconfigured to: receive one or more second uplink digital RF signals fromthe upstream digital bus interface; provide the one or more seconduplink digital RF signals to the downstream digital bus interface;receive one or more third uplink digital RF signals from the downstreamdigital bus interface; provide the one or more third uplink digital RFsignals to the upstream digital bus interface; and combine one or morerespective second uplink digital RF signals and one or more respectivethird uplink digital RF signals to generate the uplink digital RFsignal, wherein the one or more respective second uplink digital RFsignals and the one or more respective third uplink digital RF signalsare programmably determined by the digital signal processing controlleramong the one or more second uplink digital RF signals and the one ormore third uplink digital RF signals, respectively.
 10. The DIM of claim8, wherein the digital signal processing circuit is further configuredto: receive an uplink digital baseband signal from the digital signalsource via the digital communications interface; convert the uplinkdigital baseband signal to generate one or more fourth uplink digital RFsignals; provide the one or more fourth uplink digital RF signals to thedownstream digital bus interface; provide the one or more fourth uplinkdigital RF signals to the upstream digital bus interface; and combineone or more respective fourth uplink digital RF signals to the uplinkdigital RF signal, wherein the one or more respective fourth uplinkdigital RF signals are programmably determined by the digital signalprocessing controller among the one or more fourth uplink digital RFsignals.
 11. The DIM of claim 10, wherein the uplink digital basebandsignal is configured to be in compliance with a common public radiointerface (CPRI) format.
 12. The DIM of claim 8, further comprising adigital-to-analog (D/A) converter coupled to the analog localdistribution interface, wherein the D/A converter is configured to:convert the uplink digital RF signal to generate an uplink analog RFsignal; and provide the uplink analog RF signal to the analog localdistribution interface.
 13. The DIM of claim 3, wherein the downlinkdigital baseband signal is configured to be in compliance with a commonpublic radio interface (CPRI) format.